Gatorade is good too, it replenishes your electrolytes, you know what's better honestly? It sounds weird, but it's the truth is, pedialyte is even better for you.
Tomatoes though is a good source of Folate, which is good for the brain, not to mention there are other vitamins in it that are helpful in giving the body nutrition after a heavy night of drinking.
I used to have the worst hangovers until IAG recommended that to me.
If you're feeling sleepy or groggy, try smelling, or consuming a variety of citrus, like oranges and lemons, as it helps to stimulate you.
The elixir is 1/4 (for me one half) tomato juice, preferably V8 for the extra nutrients, and 3/4 (again half for me) beer.
Pickle juice, although a diuretic, helps too. I don't know why, but it does, especially if you have been drinking hard liquor. Not a lot though, just a gulp or two.